I've been using vv ego batteries for most of my vaping time - they just give that bit of 'oomph' to your vape (very technical
) You just up the volts until you get a really satisfying vape.
I've recently bought an itaste mvp (best price I found here) I would say it's better than your standard vv battery, but it's a bit chunky. Fine for using at home, too big to use when driving and too big to be inconspicuous when out and about. Big positive is battery life - it's a 2600 mah battery and lasts me 3-4 days. It shows a green light, then yellow, then red to indicate battery charge, so you won't get caught out with a spent battery when you're out. It has a puff counter too which I only really bothered looking at for the first few days. You can also still use it while it is charging.
It came with an iclear 30 which I was looking forward to trying, but I'm not a fan of it. I don't like the metal mouth piece and I felt it left a metallic taste in my mouth - could be to do with the juice I use (pchela's famous 5 which is a butterscotch/caramel/chocolate mix) I've gone straight back to my iclear 16's that I've been using for ages.
If anyone wants to buy the iclear 30 from me for a fiver including postage send me a pm - used for half a tank with p5, washed out and left to air dry.
I also mix my own juice if you have any questions.